In a conventional optical disk drive, as disclosed in Japanese Patent Laid-Open No. 10-302402 and Japanese Patent Laid-Open No. 11-162105, generation of a data storage address in a buffer memory that is storage means used for an error correction processing of data read from an optical disk and data transfer to a host computer is carried out in the following manner.
That is, detection and interpolation of various synchronization patterns indicating a beginning of data structure (ECC block synchronization, sector synchronization, frame synchronization) are carried out, and the data storage address in the buffer memory is controlled according to the various synchronization detection and interpolation signals.
That is, the address generation has been carried out in such a manner that the number of various synchronization detection and interpolation signals is reflected as is in the data storage address in the buffer memory.
Furthermore, in order to prevent an abnormality from occurring in the data storage address in the buffer memory, the detection and interpolation of the various synchronization signals have been enhanced.
In the case where such an optical disk drive is used that the number of the various synchronization detection and interpolation signals corresponds to the data storage address in the buffer memory as described above, there has been a problem that the correspondence between pieces of data stored in the buffer memory is lost before and after the abnormality in the synchronization signals by an abnormality occurring in the synchronization detection and interpolation signals, such as omission or error in detection, or failed interpolation, that is caused by factors such as a fingerprint or scratch on the optical disk medium.
That is, there is a problem (first problem) that when an abnormality is caused in the synchronization detection and interpolation signals by factors such as a fingerprint or scratch on the optical disk medium, the correspondence between pieces of data stored in the buffer memory is lost.
Furthermore, there has been a problem that if the correspondence between pieces of data stored in the buffer memory is lost by the above-described factors, the data read from the optical disk medium is difficult to be properly replayed even with error correcting means.
That is, there is a problem (second problem) that if the correspondence between pieces of data stored in the buffer memory is lost by the above-described factors, the data read from the optical disk medium is difficult to be properly replayed even with error correcting means.
In addition, there has been a problem that in case of the optical disk medium having defective sector information recorded therein, there has been a problem that it is difficult to read data from the optical disk medium unless the defective sector information is acquired from the optical disk medium and the defective sector is indicated.
That is, there is a problem (third problem) that in case of the optical disk medium having defective sector information recorded therein, there has been a problem that it is difficult to read data from the optical disk medium unless the defective sector information is acquired from the optical disk medium and the defective sector is indicated.